Our conceptions, our religions, our philosophies, are not only individual phenomena; they are also and chiefly social phenomena, moments in a collective and continuous life, of which all the phases are interdependent. We only know in a given order of knowledge, what is compatible at that moment with the generally admitted philosophy, with the knowledge already acquired in this and in the other orders of phenomena, with the great hypotheses considered as true, with the methods in force, etc. As soon as the human mind has become conscious of the evolution to which it is subject, as soon as it has grasped its most general law (the law of the three states), in a word, as soon as sociology is founded, science can no longer be conceived as other than relative. For from that moment the various sciences appear as so many great social facts, which vary as so many functions of the rest of civilisation. Our speculations, “depending on the totality of social progression,” can therefore never admit of that absolute fixity which metaphysicians have supposed. The continuous movement of history modifies, in the long run, the beliefs which appear to be the most immutable. Our theories tend to represent more and more faithfully the objects of our investigations, that is to say the laws of phenomena. We are thus brought back to the idea of limit, which is never attained, towards which we are advancing by means of approximations ever more exact. The time is not yet far distant, when a doctrine of this kind could not have been advanced without at once being rejected as sceptical. The human mind is scarcely beginning to understand that truth cannot be immutable.[45] Men believed that truth must always be identical with itself, always identical for all minds at all times and at all places. It seems that in losing this character, it must cease to be truth. That is why philosophy has been so persistent in the pursuit of the absolute. It was believed that no truth could be certain, unless it rested, ultimately, upon an immutable foundation. Science was therefore made to hang on metaphysics. And the defeats, a thousand times repeated, of metaphysics would not have discouraged the human mind had not positive philosophy at last shown that the truth of which we are capable, because it is relative does not cease to be truth. We are not condemned to choose between the pursuit of an inaccessible absolute and the crumbling down of all science. It suffices to understand that human science evolves and that this evolution is subject to laws. It is never ended: it always “becomes.” It is not a “state:” it is a “progress.”